Microwaves are electromagnetic waves with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz.

In microwave ovens microwaves or radio waves are used.

When cake is put into a microwave oven then microwaves are absorbed by the cake. And these waves produces motion in molecules of the cake and as a result, they start colliding with each other and hence the cake swallows up.

A polymer is a large molecule (macromolecule) composed of repeating structural units. These subunits are typically connected by covalent chemical bonds. Because of the extraordinary range of properties of polymeric materials, they play an essential role in everyday life.

There are many polymers in nature. e.g. in trees, insects, animals and in our food also.

D.N.A. is also a polymer which help in human growth.

In baby napkins, a polymer 'Sodium polyacrylate'  is used. 

This Polymer is also known as water-lock, because this polymer can absorb 200 times water as compared to the size of this polymer.

COCONUT

Coconut water has a high potassium content and contains antioxidants linked to a variety of health benefits. The Water in coconut is very very closely similar to human blood plasma. 

In the IInd world war when soldiers got wounded, they needed the blood. Then to save their lives coconut water IV's were used by the British and Japanese.